1. Field of the Invention
The present invention relates to an optical apparatus having dust-off function, in which dust adhering to the inside of the optical apparatus can be removed, and more specifically, to an optical apparatus having a dust-off function for an image-pickup element such as an electronic image-pickup apparatus (digital camera or the like), an image display element such as a projector apparatus, and capable of also detecting an abnormal state of the dust-off function.
2. Description of the Related Art
In an electronic image-pickup apparatus such as a digital camera, various mechanisms that mechanically operate are arranged in its apparatus body. Therefore, dust and the like that are generated from the mechanisms adhere to the photoelectric conversion surface of an image-pickup element, thereby inevitably degrading photographed images. Further, in a projector apparatus, there is the problem as well that dust or the like is inhaled to the inside thereof by a cooling fan, and the dust or the like is adhered to a display surface of an image display element.
Accordingly, a technique is proposed as an example of a technique related to the dust-off function. According to this technique, dust or the like adhering to a protective glass plate (referred to as “dust-off glass” or “dust-off filter”) for protecting the image-pickup element is shaken off by vibrating the protective glass plate. In a prior art system, therefore, a piezoelectric element is provided as means for vibrating the protective glass plate, for example. The protective glass plate that is attached to the piezoelectric element is vibrated with a given period by utilizing the behavior of the piezoelectric element to extend or contract in response to cyclic voltage applied thereto.
The present invention's first object is to provide an optical apparatus having dust-off function that includes a system such that a protective glass in an optical apparatus that has a dust-off function for shaking off dust or the like adhering to the protective glass on the front face of an optical electronic device such as an image-pickup element, an image display element, or the like, by vibrating the protective glass. A second object is to provide an optical apparatus having dust-off function in which trouble in its dust-off function can be detected with ease.